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<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    function WebSocketTest(url, params = {}) {
      return new Promise((resolve, reject) => {
        const socket = new WebSocket(url)
        socket.onopen = () => {
          socket.send(JSON.stringify(params))
        }
        socket.onmessage = (event) => {
          console.log(event.data)
          resolve(event.data)
        }
      })
    }


    WebSocketTest('ws://localhost:3000', { age: 18 }).then(res => {
      console.log(res)
    })
  </script>
</body>

</html>